Multirate, constant envelope, constant bandwidth, modulation, channelization, and detection system based on orthogonal bipolar spreading vectors including biorthogonal coding and including error-control
First Claim
1. A multirate communication system comprising:
- a set of orthogonal spreading modulation vectors, each vector 2v chips in length, where v is any positive integer, each modulation vector supporting the transfer of information at a first information rate;
a first subset of the set of modulation vectors defining biorthogonal codewords for biorthogonal coding of information;
a second subset of the set of modulation vectors supporting the transfer of information at an information rate 2n times the first information rate, where n is any positive integer, with the exclusion of (2n-1) vectors in said set not orthogonal to the first 2(v-n) chips of said modulation vector;
a transmitter for modulating and transmitting information over said set of modulation vectors; and
a receiver for receiving and demodulating information over said modulation vectors.
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Accused Products
Abstract
A modulation channelization, demodulation and error-control system based on orthogonal bipolar spreading vectors is provided that permits a variable information rate to be transmitted without inducing envelope fluctuations and which permits multiple access without requiring the transmitter amplifier to support the combined information rate of all users. The modulation system uses the Hadamard matrix vectors to form communication channels. The information rate on any channel may be doubled by using half the vector length to transmit information. The vector that is not orthogonal-in-the-half to the rate-doubled vector is deactivated. Similarly, higher information rates may be provided through truncation of the transmission vector and the elimination of the resultant non-orthogonal vectors. The system provides biorthogonal coding in addition to multirate communication. A multi-channel receiver including a Fast Hadamard Transform structure comprised of controllable modified logic cells for performing the multi-rate communication of the present invention is illustrated.
9 Citations
15 Claims
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1. A multirate communication system comprising:
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a set of orthogonal spreading modulation vectors, each vector 2v chips in length, where v is any positive integer, each modulation vector supporting the transfer of information at a first information rate;
a first subset of the set of modulation vectors defining biorthogonal codewords for biorthogonal coding of information;
a second subset of the set of modulation vectors supporting the transfer of information at an information rate 2n times the first information rate, where n is any positive integer, with the exclusion of (2n-1) vectors in said set not orthogonal to the first 2(v-n) chips of said modulation vector;
a transmitter for modulating and transmitting information over said set of modulation vectors; and
a receiver for receiving and demodulating information over said modulation vectors. - View Dependent Claims (2, 3)
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4. A multirate receiver comprising:
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an adaptable modified Fast Hadamard Transform (FHT) operating on the vectors of a Hadamard matrix, said FHT comprised of logic cells that may be set b either a pass or combine mode to allow multirate communication over the vectors of the Hadamard matrix;
a selection logic selecting either pass or combine mode for logic cells of said adaptable FHT in response to channel rate selections;
a sign detector detecting the sign of a received observable vector;
a magnitude selector for selecting the largest correlation of a received observable vector to a biorthogonal code selection; and
a biorthogonal output former receiving the largest correlation selected by said magnitude selector and the sign detected by said sign detector and decoding received information. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. A method for transmitting information comprising:
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forming a set of orthogonal spreading modulation vectors having a first length;
forming a first subset and a second subset of aid modulation vectors;
transmitting information at a first information rate using a first vector of said first subset of vectors having said first length;
transmitting information at a second information rate using a portion of a second vector of said first subset of vectors, said portion of said second vector orthogonal to said first vector;
transmitting information using biorthogonal coding of the vectors in said second subset;
refraining from transmitting using any vector in said first subset not orthogonal to said portion of said second vector;
refraining from transmitting using any vector in said first subset not orthogonal to the vectors of said second subset;
receiving and demodulating said information transmitted at said first and second information rates and with said biorthogonal coding. - View Dependent Claims (12, 13, 14, 15)
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Specification